Disease relevance of MYO1

• Identification of a 180 kD protein in Escherichia coli related to a yeast heavy-chain myosin [1].

Psychiatry related information on MYO1

• This motor activity requires hydrolysis of ATP, does not require cytosolic extracts, is sensitive to protease treatment, and displays an ATP concentration dependence similar to that of members of the myosin family of actin-based motors [2].

High impact information on MYO1

• The X-ray crystal structure of Vik1 exhibits a similar fold to the kinesin and myosin catalytic head, but lacks an ATP binding site [3].
• The organization of the motor protein myosin into motile cellular structures requires precise temporal and spatial control [4].
• Caenorhabditis elegans UNC-45 facilitates this by functioning both as a chaperone and as a Hsp90 cochaperone for myosin during thick filament assembly [4].
• Asymmetric accumulation of Ash1p in postanaphase nuclei depends on a myosin and restricts yeast mating-type switching to mother cells [5].
• Mother cell-specific HO expression in budding yeast depends on the unconventional myosin myo4p and other cytoplasmic proteins [6].

Chemical compound and disease context of MYO1

• Analysis using this assay further demonstrated that the motor activity of these myosins is required for the polymerization step, and that actin polymerization depends on phosphorylation of myosin motor domain by p21-activated kinases (PAKs), downstream effectors of the small guanosine triphosphatase, Cdc42p [7].

Biological context of MYO1

• The yeast MYO1 gene encoding a myosin-like protein required for cell division [8].
• The MYO1 gene from Saccharomyces cerevisiae: its complete nucleotide sequence [9].
• It is suggested that this phenotype is the cause of the cell division defect and the osmotic sensitivity of yeast MYO1 mutants [10].
• We have completed the nucleotide sequence of the yeast MYO1 gene and deduced its amino acid sequence [11].
• The Myo1p ring remains in the mother-bud neck until the end of anaphase, when a ring of F-actin forms in association with it [12].

Anatomical context of MYO1

• In this study, we report that a disruption mutant in the rod portion of the yeast myosin heavy chain gene, MYO1, produces abnormal chitin distribution and cell wall organization at the mother-bud neck in a high proportion of dividing cells [10].
• MYO2 encodes a type V myosin heavy chain needed for the targeting of vacuoles and secretory vesicles to the growing bud of yeast [13].
• The COOH-terminal domain of Myo2p, a yeast myosin V, has a direct role in secretory vesicle targeting [13].
• A type V myosin (Myo2p) and a Rab-like G-protein (Ypt11p) are required for retention of newly inherited mitochondria in yeast cells during cell division [14].
• These results suggest that a contractile actin-myosin based cytokinetic mechanism appeared early in the evolution of eukaryotic cells and further emphasise the utility of fission yeast as a model organism in which to study the molecular and cellular basis of cytokinesis [15].

Associations of MYO1 with chemical compounds

• The wild-type MYO2 gene encodes an essential form of myosin composed of an NH2-terminal domain typical of the globular, actin-binding domain of other myosins [16].
• Crystallization, X-ray characterization and selenomethionine phasing of Mlc1p bound to IQ motifs from myosin V [17].
• The motile activities of the small, single-headed class I myosins (myosin I) from the lower eukaryotes Acanthamoeba and Dictyostelium are activated by phosphorylation of a single serine or threonine residue in the head domain of the heavy chain [18].
• Vasoconstrictor and vasodilator pathways inhibit and activate myosin phosphatase, respectively [19].
• Starting with Cys-lite constructs of both yeast actin (ActC) and the Dictyostelium myosin II motor domain (S1dC), site-directed labeling (SDL) mutants were generated by mutating residues to Cys in the proposed weak and strong-binding interfaces [20].

Physical interactions of MYO1

• Mlc1p is also shown to interact with the class II conventional myosin (Myo1p) [21].
• The UCS domain protein She4p binds to myosin motor domains and is essential for class I and class V myosin function [22].
• Protease digestion of mitochondrial outer membrane proteins or saturation of myosin-binding sites on F-actin with the S1 subfragment of skeletal myosin block binding [23].
• Calmodulin could bind to Myo1p through the IQ domain at the neck [24].
• Moreover, Rvs167p functionally interacts with the myosin Myo2p [25].

Enzymatic interactions of MYO1

• In this paper we show that PAK1 has similar substrate specificity as MIHCK when assayed against synthetic substrates and that PAK1 phosphorylates the heavy chain (1 mol of P(i) per mol) and activates Acanthamoeba myosin I as MIHCK does [26].
• Yeast actin mutants with acidic residues at the N terminus either neutralized (DNEQ) or deleted (delta-DSE) were used to assess the role of N-terminal acidic residues in the interactions of actin with myosin in the contractile cycle [27].

Regulatory relationships of MYO1

• These results suggest that Mti1p and Vrp1p antagonistically regulate type I myosin functions [28].
• An intact SH3 domain is required for myosin I-induced actin polymerization [29].
• In striated muscle, tropomyosin regulates contractility by sterically blocking myosin-binding sites on actin in the relaxed state [30].
• Cytokinesis in eukaryotes involves the regulated assembly and contraction of a ring comprising filamentous (F)-actin and myosin II [31].
• Cloning and characterization of a Dictyostelium myosin I heavy chain kinase activated by Cdc42 and Rac [18].

Other interactions of MYO1

• Motor proteins in cells include myosin, which is actin-based, and kinesin, dynein and dynamin, which are microtubule-based [32].
• Sequential assembly of myosin II, an IQGAP-like protein, and filamentous actin to a ring structure involved in budding yeast cytokinesis [33].
• Roles of type II myosin and a tropomyosin isoform in retrograde actin flow in budding yeast [34].
• Deletion of MYO3, a yeast gene encoding a "classic" myosin I, has no detectable phenotype [35].
• We also identify Mlc2p as the regulatory light chain for Myo1p and demonstrate its role in Myo1p ring disassembly, a function likely conserved among eukaryotes [36].

Analytical, diagnostic and therapeutic context of MYO1

• Indirect immunofluorescence studies using epitope-tagged Myo5p indicate that Myo5p is localized at actin patches [35].
• Remarkably, the tail alone of budding yeast Myo1p localizes to the contractile ring, supporting both its constriction and cytokinesis [37].
• OBJECTIVE: To determine whether cell cycle changes can be detected in myosin II-deficient cells using flow cytometry techniques [38].
• We examined the distribution of ABP and myosin molecules in acetone-fixed rabbit lung macrophages by means of immunofluorescence [39].
• Co-immunoprecipitation, two-hybrid and overlay assays demonstrated that Cmd1p interacts with Myo5p, a type I unconventional myosin [40].

References